Copper alloy



Patented Jan. 22, 1935 UNITED STATES PATENT orrlcs COPPER ALLOY Michael George Corson, Jackson Heights, N. Y.,

assignor of three-twentieths to George H. a Corey, Bayside, N. Y.

No Drawing. Application March 2, 1929, Serial No. 344,089. Renewed May 9, 1933 4 Claims. (C 75-1) This invention relates to alloy compositions, and plex brasses in their ability to be hot worked when particularly to the type of alloys consisting prinbrought into the beta state and to retain a high cipally of copper, tin and zinc, and containing also strength with considerable ductility in the cold small but effective amounts of nickel, and charstate. Also, they possess the property of high tin 5 acterized, when treated according to the process bronzes of being able to form a well distributed 5 hereinafter disclosed, by properties giving them delta tin constituent of high hardness, which special utility when used in forming lubricated makes them good for wear resistance, not only wearing surfaces, such, for example, as in bearbecause of the inherent hardness of such conings, bushings, pump cylinders, gears, etc. stituent, but also because the uniform distribution The most important feature of the copper-tin 0f the delta constituent in suitably sized particles alloys (tin bronzes) that causes them to be espeu out the ound a matrix imparts t0 cially suitable for use in bearings and in similar a w arin rface prep red therefr m h ili situations where resistance to wear is desirable, to become covered with a substantial film of lubriis their peculiar structure in the cast state, which cant in the regions occupied by the softer alpha is characterized by the presence of a soft ground Constituent Of the matrix. 10

mass serving as a matrix for, and containing As described and claimed in my copending inclusions of, a second constituent,the beta or application Serial No. 340,651, new Patent No. the delta phase-of considerable hardness, so 6, which t pp o is in P forming a very desirable complex possessing good a continuation, I have also found that such terbearing qualities. nary bronzes can be markedly improved by struc- 20 Other alloys used for bearings, or more spetural changes resulting from a process of heat cifically for bushings, are certain high zinc treatment. As pointed out in the aforesaid patbrasses composed of a high proportion of copper ent, such bronzes may contain additions of other in alpha phase and a low proportion in beta or in l m nts i ludin ni a um a d mandelta phase. These alloys, while they are cheaper san s whi h if pr s nt in r l d Pr p rti ns 25 than the high tin bronzes and can be hot worked hav fic al effects on these alloys both in with ease, since at high temperatures they transtheir as cast condition and in their heat treated form into a uniform beta phase, are less satisfacti tory for bearing purposes than the tin bronzes, Alloys coming within the Present v i n n either because of insufiicient hardness (too great e p p Within the following a e of P 30 a proportion of the softer alpha phase as comportions:

pared with the harder beta phase) or because of Tm 7 the distribution of the harder phase in the softer Zinc 10-357 ground mass in such a way as to present an ex- Nickel Small amounts up to cessive amount thereof at the wearing surface Coppe; 0 Balance 35 with consequent lack of ability to retain an adequate oil film thereon, The amounts of zinc and tin depend each upon While alpha copper alloys are workable cold the Other- The more Zilw e alloy contains, the and to a slight extent when hot and the beta alloys 1958 till it may contain Nickel additions Within 40 are all workable hot, such alloys as are built up the range specified, and preferably around 2 to 40 of mixtures of the alpha and beta phases, at any improve the Strength and d c the brittle temperature below the freezing point, are not 11655 Or the resulting y- It is found furthereasily workable by pressure or tension either in more that the Presence of nickel Works decided the hot or cold state, improvement in the resulting structure and ac- 4 High t bronzes are t exempt from t celerates the changes that take place during heat action of this rule. The bronzes containing betreatment- Either a P Of the tin r he Zinc tween 6 and 18% tin cannot be worked while hot. may be replaced y about half its Weight o alu- Such alloys containing above 18% and up to 27%, 11111111111, aluminum P e however, ot being tin are easily workable while hot, but are relaadded in amounts greatly exceeding of the tively expensive, and, what is more important, total- These ys y also tain small are at room temperatures too brittle and hard amounts of magnesium. phosphorus, ilicon or throughout their structure to be useful as strucma n d deoxidizelsn uminum tural materials or for bearings and bushings. is present, amounts of manganese up to 4% may I have found that ternary copper-tin-zinc be added with very beneficial results as more fully bronzes can be made to behave much like comhereinafter set fort d fl i amuunts of from 0.3 to 2.0% may also form useful but not absolutely necessary additions. I have also found that the properties of .the alloys of this class as regards their ability to be worked by cutting or 5 machining may be further improved by adding up to about 3% of lead.

\ As above indicated, I have found that it is desirable to add both manganese and aluminum for some purposes. This is recommended where increased strength and forgeability are desired. Preferably,.aluminum and manganese should be added in about the relative proportions of one part of aluminumto two parts of manganese, since it appears that the improved properties imparted by the presence 01' aluminum and manganese are due to the formation of a hard compound, probably MnAl, which gives increased strength. to the matrix.

These alloys can be used as cast or be hot worked by forging, rolling, or especially, by extrusion; but to improve their structural properties for use informing bearings and for similar purposes it is advisable to subject them to heat treatment.

According to a preferred form of heat treatment, the cast or hot worked piece is heated up to or above a point where the alloy forms a homogeneous beta phase or a mixture of the two betas possible-650-800 0., according to the composition,-and then quenched or air cooled. This brings it into a hard martensitoidal or acicular form. It is next heated to a point above the eutectoidal point, or from 550-625 C., and kept at this temperature for from one to six hours, or until the acicular structure is destroyed and the beta phase divorces from the alpha, the first coalescing in the form of well-rounded dense grainlets sufliciently well spaced within the matrix of alpha to permit the formation of a lubricating film on the surface when in use.

The next step consists in lowering the temperature preferably to 450*-525 0., and not below 250 0., and holding such temperature for such time as to allow the beta phase to dissociate into alpha plus delta, the latter forming very fine particles within each original grainlet of beta. When this condition'is reached the structure will have become stabilized.

when the alloy contains amounts of manganese and aluminum within the range hereinbefore indicated, the heat treatment may be still further modified. According to this further modification. the cast or hot worked piece is heated as in the first instance above mentioned to above the range 650"-850 0., according to the composition, and preferably to or above 750 C., and then quickly-cooled as by quenching or air cooling. The product so treated is then reheated to within the range 250-525 C. and held forapproximately one hour or until the delta constituent precipitates and becomes stabilized, whereupon it may be permitted to cool either slowly or rapidly.

What I claim is: g

1. A composition of matter consisting principally of copper and containing 4-l8% tin, 10-35% zinc, a substantial and effective amount but not exceeding 10% of nickel, and being substantially free from carbon; said composition' being capable when subjected to heat treatment of assuming a physical structure characterized by the presence of beta crystals substantially uniformly distributedthroughout a matrix of alpha crystals.

2. A composition of matter consisting principally of copper and containing 448% tin, 10-35 zinc and about 2-3% of nickel, and ,being substantially free from carbon; said composition being capable when subjected to heat treatment of assuming a physical structure characterized by the presence of beta crystals substantially uniformly distributed throughout a matrix of alpha crystals.

3. A bronze alloy consisting of 4-18% tin, l0-35% zinc, about 2-3% nickel, substantial and efiective amounts of aluminum and manganese, but not exceeding 2% aluminum and 4% manganese, with the balance principally copper, and

being substantially free from carbon; said alloy being capable when subjected to heat treatment of assuming a physical structure characterized by the presence of beta crystals substantially uniformly distributed throughout a matrix of alpha crystals.

4.A bronze alloy consisting of 4-18% tin, 10-35 zinc, substantial and effective amounts of nickel, aluminum, manganese and lead, but not exceeding 10% nickel, 2 aluminum, 4% manganese and 3% lead, with the balance principally copper, and being substantially free from carbon; said alloy being capable when subjected to heat treatment of assuming a physical structure characterized by the presence of beta crystals substantially uniformly distributed throughout a matrix of alpha crystals.

MICHAEL GEORGE CORSON. 

